* Brega oil town changed hands often early in conflict
* Eastern front has been relatively calm for several weeks
* NATO bombarded Gaddafi loyalist positions in Brega area
By Maria Golovnina
AJDABIYAH, Libya, June 14 (Reuters) - Rebels opposed to Libyan leader Muammar Gaddafi advanced westward on Tuesday aiming to retake the oil town of Brega in a push to extend their control over the east of the country.
The rebels launched their new offensive on Sunday. The fighting has killed 13 and wounded dozens, they said.
Blasts rumbled in the distance near Brega, which has changed hands several times between rebels and forces loyal to Gaddafi since the revolt against his four-decade rule erupted in mid-February. Pick-ups mounted with guns sped down the road towards the town.
After a series of earlier battles, the sprawling coastal town that is home to an oil export terminal and other oil installations has been in Gaddafi’s control since late April, largely uncontested as rebels regrouped in the east.
“We are pushing for Brega. We are optimistic. Two days ago we received 50 wounded and 7 dead and yesterday, 37 wounded and 6 dead. Today it is quiet so far, but we are ready for new casualties,” said Mohamed Abdel-Karim, a doctor at Ajdabiyah hospital.
NATO forces have bombarded Gaddafi loyalist positions in the Brega area in past weeks and have used attack helicopters, deployed to enable more accurate targeting of the Libyan leader’s forces.
At a rebel checkpoint on the western entrance to Ajdabiyah, which is an 860 km (540 mile) drive from Tripoli, four trucks carrying armoured personnel carriers headed towards Brega. Rebel fighters seated on top cheered, waved and fired in the air.
A convoy of dozens of pick-ups, mounted with machineguns, sped along the road towards Brega, 75 km west of Ajdabiyah.
“There is fighting happening there right now. We have advanced to 20 km outside Brega. They (rebels) are advancing now. Very soon they will be in Brega,” said fighter Osman al-Maghrabi, 35, who used to serve in Gaddafi’s army.
“I think we will be having Friday prayers in Brega this week,” he said.
Much of the heaviest fighting between rebels and Gaddafi’s forces has been closer to the capital. Rebel forces in Misrata, about 190 km east of Tripoli, have been advancing slowly.
Misrata fought off weeks of assaults by Gaddafi’s forces, relying on supplies brought in by sea, often from the rebel stronghold of Benghazi in eastern Libya, home to the rebel National Transitional Council.
Fighting also rages to the west of Tripoli, mainly in mountain areas above the coastal plain.
Rebels had initially sought to push west from the eastern half of Libya, a restive region that quickly fell out of Gaddafi’s control.
The rebels had raced along the main coast road from Ajdabiyah to Brega, Ras Lanuf and beyond but were thrown back, more than once, by Gaddafi’s superior firepower.
The eastern front has been relatively calm in recent weeks.
“It was never entirely quiet in this hospital. Now there is a lot more happening. Our revolutionaries are fighting hard. They are united and they will take Brega soon. Gaddafi will not last long,” said a junior doctor in Ajdabiyah hospital, who gave his name only as Khaled. (Writing by Edmund Blair in Cairo; Editing by Janet Lawrence)